Temperature effect on seed germination of Lupinus albus, Lupinus angustifolius and Lupinus luteus.

In order to evaluate germination response to temperature of two varieties of Lupinus albus L. (‘Luxor’, ‘Rosetta’), L. angustifolius L. (‘Jindalee’, ‘Sonet’) and L. luteus L. (‘Dukat’, ‘Mister’), seeds were subjected to seven different germination temperatures from 5°C to 35°C with step of 5°C. Germination percentage and Mean Germination Time (MGT) were evaluated. Radical elongation was also measured at temperature of 20°C. L. albus showed an optimal temperatures range from 10 to 30°C with germination next to 100% and with a MGT decreasing from 10 to 3 days in the same temperature range. Among varieties, in L. albus, ‘Rosetta’ seems to be more tolerant to extreme (low and high) temperatures compared to ‘Luxor’. L. angustifolius and L. luteus showed full germination from 5 to 25°C, while at temperatures over 30°C germination lower than 50% was recorded. MGT ranged between 9 and 2 days. In L. angustifolius, ‘Jindalee’ was less tolerant of ‘Sonet’ to highest temperatures and in L. luteus, ‘Dukat’ showed better germination response to high temperatures compared to ‘Mister’. Root elongation varied in relation to varieties.